ABSTRACT
Signal Transducers (STATs) 1 and 3 and Activator Protein 1 (AP-1) are transcription factors involved in the development of malignancy in colorectal carcinoma (CRC). Matrix Metalloproteinase 1 (MMP-1) is a protease frequently dysregulated in de-differentiated and invasive cancer cells. Its expression is influenced by STAT and AP-1 transcription factors. We studied their contributions to transcriptional regulation of MMP-1 in colorectal carcinoma (CRC) cells. Both STAT3 and AP-1 contribute individual expression-inducing and additive effects and interact with the MMP-1 promoter. DNA binding of AP-1 protein c-Jun is stimulation-independent but modulated by STAT3 and a STAT recognition DNA element. Activated STAT3 showed a suppressive effect on AP-1-mediated MMP-1 mRNA upregulation as shown by STAT3 knockdown. Surprisingly, activated STAT1 overcame STAT3-dependent repression of AP-1-driven MMP-1 expression. Moreover, combined STAT3, STAT1 and AP-1 activities evoked maximal MMP-1 mRNA levels in a synergistic manner. Our results suggest a dominant role of AP-1 in transcriptional upregulation of MMP-1 in CRC cells which is modulated by joint functions of STAT3 and STAT1. The individual and combinatorial activity of these factors is of diagnostic and prognostic interest.
Subject(s)
Colorectal Neoplasms , Gene Expression Regulation, Neoplastic , Matrix Metalloproteinase 1 , Promoter Regions, Genetic , STAT1 Transcription Factor , STAT3 Transcription Factor , Transcription Factor AP-1 , Cell Line, Tumor , Colorectal Neoplasms/enzymology , Colorectal Neoplasms/genetics , Gene Expression Regulation, Neoplastic/genetics , Humans , Matrix Metalloproteinase 1/genetics , Matrix Metalloproteinase 1/metabolism , Promoter Regions, Genetic/genetics , STAT1 Transcription Factor/metabolism , STAT3 Transcription Factor/metabolism , Transcription Factor AP-1/metabolismABSTRACT
BACKGROUND: The histopathological structure of malignant tumours involves two essential compartments - the tumour parenchyma with the actual transformed cells, and the supportive tumour stroma. The latter consists of specialized mesenchymal cells, such as fibroblasts, macrophages, lymphocytes and vascular cells, as well as of their secreted products, including components of the extracellular matrix, matrix modifying enzymes and numerous regulatory growth factors and cytokines. In consequence, the tumour stroma has the ability to influence virtually all aspects of tumour development and progression, including therapeutic response. AIM: In this article we review the current knowledge of tumor stroma interactions in urothelial carcinoma and present various experimental systems that are currently in use to unravel the biological basis of these heterotypic cell interactions. RESULTS: For urothelial carcinoma, an extensive tumour stroma is quite typical and markers of activated fibroblasts correlate significantly with clinical parameters of advanced disease. Another clinically important variable is provided by the stromal expression of syndecan-1. CONCLUSION: Integration of markers of activated stroma into clinical risk evaluation could aid to better stratification of urothelial bladder carcinoma patients. Elucidation of biological mechanisms underlying tumour-stroma interactions could provide new therapeutical targets.
